Mapping the terrestrial gamma radiation dose

The Tellus airborne radiometric data have enabled assessments of environmental radioactivity levels in unprecedented detail across the north of the island of Ireland. Both the natural (geological) and man-made (industrial) contributions to public exposure from ionising terrestrial gamma radiation are considered. Over much of the area the gamma-ray flux is significantly attenuated by peat and organic soil but relatively highly radioactive rocks are exposed in places, notably in the south-east of the surveyed area. The results indicate that across the area the effective dose from terrestrial gamma radiation is everywhere within the acceptable level, subject to the inherent spatial averaging of the measurements. The airborne survey also revealed areas where industry has concentrated or exposed naturally occurring radioactive material, including quarries and fly-ash piles.